#include <stdio.h>

int main() {
    float score;
    char grade;
    
    printf("请输入学生成绩(0-100): ");
    scanf("%f", &score);
    
    if (score < 0 || score > 100) {
        printf("出错提示: 成绩应在0-100之间！\n");
        return 1;
    }
    
    // 判断等级
    if (score >= 90) {
        grade = 'A';
    } else if (score >= 80) {
        grade = 'B';
    } else if (score >= 70) {
        grade = 'C';
    } else if (score >= 60) {
        grade = 'D';
    } else {
        grade = 'E';
    }
    
    printf("成绩等级: %c\n", grade);
    return 0;
}